Field of the Invention
The invention relates to a device mounted on the tube barrel of a weapon, especially on an aircraft cannon to act as an acoustical wave suppressor or muzzle-brake. A casing tube is attached at the muzzle end of the tube barrel by a holding means, and serves to take up a shock wave at the muzzle. The casing tube possesses a rear opening and, aligned in the direction of shooting, a front opening, through which a fired projectile exits.
Upon firing a projectile by a cannon there is, in addition to the weapon recoil force, a shock wave at the muzzle of the barrel of the cannon. This wave produces a violent surge of acoustic pressure. The blast wave moves away from the muzzle in the form of a vortex ring. The pressure field of this vortex ring causes the structural loading with alternate over-pressure followed by under-pressure. All adjacent structures are affected and all the equipment arranged at this point, most particularly sensor systems, are subjected to a high dynamic load.
In order to reduce these effects of the shock wave there has been a suggestion in the prior art for a muzzle brake combined with a casing tube termed a xe2x80x9cshock wave accumulatorxe2x80x9d. Since in the art such a casing tube is also termed a xe2x80x9cbottlexe2x80x9d or xe2x80x9cblast bottlexe2x80x9d, the term xe2x80x9cbottlexe2x80x9d will continue to be employed herein for the sake of uniform terminology.
The German patent publication DE 3,940,807 A1 describes such a bottle as a protective device for reducing the effects of a shock wave and of the recoil force on firing a cannon, especially one installed in aircraft.
The principle adopted here in the prior art is that the muzzle of the cannon barrel is placed in a bottle, so that between the cannon barrel and the bottle there is an intermediate space. The bottle has a muzzle brake of known type at its front end with an opening for the passage of the fired projectile and means (vanes) for deflection of the gases from the propellant charge into a direction opposite to the direction of shooting. At the rear end of the bottle a further opening is arranged for discharge of the propellant gases. In the case of this known protective device only a part of the shock wave is affected. The portion of the shock wave affected is dependent on the dimensions of the muzzle brake and is extremely limited owing to the relatively narrow passage openings. The deflection means has the effect that a part of the shock wave is deflected into the bottle, i.e. passed in a direction opposite to the direction of shooting into the rear space of the bottle and escapes after only one pass through the rear opening of the bottle. A substantial fraction of the shock wave leaves the cannon barrel through the front opening and continues to produce undesired dynamic loads on the aircraft structure and electronic components.
There is admittedly a desired effect, but the efficiency of the protective device can be substantially improved. The potential damping effects are not employed in an optimum fashion. As electronic components of military aircraft become increasingly sophisticated the need for efficient and compact muzzle brakes increases.
One object of the invention in the preferred context of aircraft is to substantially reduce the shock wave load and also the weapon recoil of a tube weapon as related to the airframe structure and the electronics of the aircraft.
This object is to be attained by attaching to the muzzle of a tube weapon an expansion chamber. The expansion chamber is generally circular in cross section and an elongated oval in sagittal section. A tube called a blast divider tube projects inwardly from the end of the expansion opposite to the muzzle along the longitudinal axis. The projectile leaving the muzzle enters and passes through the blast divider tube while muzzle blast gasses and the acoustical shock waves are deflected and broken up within the bottle.